1. Field of the Invention
The present invention relates generally to methods for providing safe working environments for blacksmithing operations and, more particularly, but not by way of limitation to methods for reducing the hazards of explosions associated with blacksmithing operations on and about containers containing vapors of a combustible liquid.
2. Brief Description of the Prior Art
In the every day operation of automobiles, it is not uncommon for ruptures to occur in the gasoline tanks thereof. For example, corrosion might result in the development of leaks in an automobile gasoline tank or a traffic mishap might rupture such a gasoline tank. If the rupture is severe the gasoline tank is usually replaced. If, however, the rupture is minor, a more common remedy is to repair the tank by, for example, sealing the rupture via soldering or welding. In some cases a patch might be soldered or welded over the rupture to seal the gasoline tank.
The hazard associated with repairing a gasoline tank by these methods is well known. The gasoline tank will usually contain small amounts of gasoline, for example, in internal crevices, and this gasoline can vaporize and mix with air inside the tank to form an explosive mixture therewith. When heat is applied to the gasoline tank to apply solder or when an arc is struck to weld the tank, the explosive mixture can ignite. The resulting explosion can seriously injure the person repairing the gasoline tank.
The danger of injury from explosive mixtures of air and gasoline vapors is by no means restricted to the repair of the gasoline tanks of automobiles. Gasoline storage tanks, such as those used to store gasoline in service stations, can also be repaired by, for example, welding or soldering. It would not be unusual for such a tank to contain remnants of gasoline which can produce an explosive mixture with air. Similarly, railway tank cars might require repair by, for example, welding.
Moreover, fluids other than gasoline can evaporate to form explosive mixtures with air. A tank car which has contained an extremely flammable industrial compound, such as, naptha or xylene, presents the hazard of an explosion when repair is carried out thereon. Such industrial compounds will produce explosive mixtures with air and such mixtures can be ignited by welding equipment or even by sparks produced by impact between portions of the car and tools.
Another common situation presenting the danger of serious injury arising from the explosion of a mixture of air and vapors produced by a combustible liquid is the reclamation of metal drums which have been used to ship the liquid. Such drums are commonly reclaimed for use as refuse containers and for other uses by cutting away various parts of the drum with an acetylene cutting torch. Explosions of mixtures of air and vapors from the liquid previously shipped in such drums during such a salvage procedure are well known.
Thus, in general, containers of many kinds present a hazard when the container has previously been used to store or transport a flammable liquid. The hazard may be brought to fruition in a number of ways. Mechanical work on the container may produce a spark which ignites vapors therein or blacksmithing operations, such as welding, soldering or cutting may ignite the vapors.